Apparatus for making paper



N 1940- c. E. YOUNGCHILD APPARATUS FOR MAKING PAPER Filed Oct. 17, 19362 Sheets-Sheet 1 QWAWQDQQ INVENTOR CAs'PE/e E. YOU/VQCH/LD.

Nov. 19, 1940. c. E. YOUNGCHILD 2,222,469

APPARATUS FOR MAKING PAPER Filed Oct. 1'7, 1956 2 Sheets-Sheet 2INVENTOR CASPE? .5 )bU/VGCH/LD.

Patented Nov. l9, 1940 APPARATUS FOR MAKING PAPER Casper E. Youngchild,Glens Falls, N. Y., assignor to International Paper Company, New York,N. Y., a corporation of New York Application October 17, 1936, SerialNo. 106,131

1 Claim.

My invention relates to a method and apparatus for making paper, or moreparticularly, to a method and apparatus for increasing the life of aFourdrinier wire, thereby lessening the cost of making paper. In greaterdetail the invention comprises the elimination of a great percentage,

- if not all, of the stresses and strains which cause Fourdrinier wiresto split adjacent their edges long before the body of the wire hasrendered full use.

It is a common experience in the use of Fourdrinier wires to find thatthe edges of the wire start to crack after several days of use, and in avery short while these cracks usually become enlarged and extendinwardly toward the center of the wire. In many instances such cracks ortears at the edge of the wire catch on a suction box or other portion ofthe mechanism and cause the wire to tear inwardly to such an extent thatit must be discarded immediately. This means that the width of paperwhich may be formed on a machine gradually, or quickly as the case maybe, decreases as the deckle straps are moved inward beyond the ends ofthe cracks until the machine is running at such lowered efllciency thatfurther use of the wire is no longer possible.

The object of my invention is to eliminate the reason for the formationof these edge cracks or tears and thereby to increase the lifetime ofthe wire to a considerable extent. In other words, the lifetime of thewire on a machine employing my invention is determined by the length oftime corrosion and friction of the wire on the rolls, suction boxes andother parts of the machine wear the wire to such an extent that the wireas a whole is obsolete. The average lifetime of a Fourdrinier wire isthereby increased several weeks and the annual expense of running aFourdrinier machine lessened by a large amount.

The full details of my invention will be apparent from the followingspecification which, taken in connection with the accompanying drawings,discloses preferred embodiments thereof.

Referring to the drawings wherein like numerals refer to like partsthroughout:

Fig. 1 schematically discloses a side elevation of a conventionalFourdrinier machine;

Fig. 2 is a plan view thereof;

Fig. 3 is a detailed view of a roll of the Fourdrinier machine, in thisinstance the breast roll, having my invention embodied thereon; and

Fig. 4 is a similar view showing an alternative form of the invention.

Referring to Fig. 1, there is disclosed the usual Fourdrinier wire I!)which consists of a foraminous, endless sheet extending about the breastroll II at the wet .end of the machine and the couch roll I2 at the dryend of the machine. In the usual machine the wire passes over drainboards [3 where the greatest percentage of the water is removed from thepulp, table rolls M where more water is removed, suction boxes l5 wherethe moisture content of the pulp is reduced to such an extent that theweb begins to appear as a sheet of paper, secondary suction boxes [6which remove more of the water and a guide roll II. The paper web formedon the wire then passes to the usual felt 2|, passing about the feltroll 22, and into the dryers and other mechanism where the water contentis reduced to a minimum and the paper is otherwise finished. The numeral23 refers to the usual dandy roll which operates tosmooth the papersurface of the web as it is being formed. The wire passes about thecouch roll l2 and contacts tensioning rolls 24, 25, 26 and 21 and thenpasses around the breast roll ll toward the mechanism previouslydescribed. The usual machine is supplied with deckle straps 28, passingabout adjustably spaced deckle pulleys 29 and 30 mounted above the wetend of the wire, for the purpose of confining the stream of pulp whileit is in extremely liquid condition at the wet end of the machine.

Referring to Fig. 2, it is seen that the distance between the inneredges of the deckle straps 28 is less than the width of the wire inorder that drainage throughout the surface of the wire will be uniform,since leakage at one or the other side of the wire would permit a suddenrush of water to disrupt the fibre formation. It is therefore apparentthat the web 20 is of lesser width than the wire III and that each edgearea of the wire is not in use as a web-forming medium. The suctionboxes l5 and I6 comprise means forcibly to withdraw water from theforming web and for this purpose consist essentially of almostcompletely closed receptacles provided with openings ,3l adjacent thesurface of the wire Ill. The suction boxes are suitably connected tosome means for producing at least a partial vacuum therein and water isdrawn through the wire and openings 3| for the purpose described. Sincethe width of the paper web is variable in accordance with the spacing ofthe deckle straps 28, the length of the openings 3| is adjustablydetermined by suitable means well known in the art in order thatportions of the wire beyond the edges of the web will not be in contactwith fcs openings communicating to the interior of the suction boxes.There is, therefore, a portion of the wire at each edge thereof whichperforms no web forming work and which is not subjected to the greaterfrictional drag of the suction boxes adjacent the area carrying the webnor exposed to the chemicals causing corrosion within the area ofdrainage. The area of drainage of the wire is therefore abraded andcorroded to a greater extent than the edge areas of the wire.

It is necessary in order that the Fourdrinier wire shall run smoothlythat it be placed under tension by the action of rolls 24, 25, 26, 21,and it also becomes necessary after long usage of the machine to regrindthe surfaces of certain of the major rolls such as rolls ll, l2, I1, 24,25, 26 and 21 since they are chemically corroded to a greater extent inthe area of drainage than at their ends. It is my discovery that theformation of edge cracks and tears in the wire (heretofore thought to bedue primarily to flapping of the edge of the wire, uneven tensionapplied to the wire, catching of the wire on edges of the suction boxes,drain boards, etc. or other causes) is due to the greater corrosion andabrasionof the wire adjacent the area of drainage and to the greaterabrasion and corrosion of the major rolls adjacent the area of drainage.Since the decrease in thickness of the wire due to the above actions isoften only a few thousandths of an inch it has always been consideredthat automatic tensioning devices or manual tensioning devices placedthe proper longitudinal strain upon all elements of the wire throughoutits width. However it will be seen, if the wire is considered a cylinderof inner radius 1;, that the amount of wear on the inner surface of thewire increases the radius by an amount 2:, and the inner circumferenceof the cylinder will be increased by an amount equal to 21:0. Thefollowing table shows that a considerable increase in the internallength of the wire results from. a very small decrease in its thickness:

Table :1: inches. "2.21:: inches. .005 -i .031416=1+in. .01 .o62s32 ,+m..15 .094248=' &+in. .02 .125664=%+in.

Therefore, in order to place the proper tension upon the major portionof the wire to prevent it from slipping after the wire has been in usefor some time, it is necessary to overload the edge portions of the wirewhich have not become worn and thus to place the edges under tensilestrains far beyond the maximum safe loads. This effect is especiallyaggravated if the rolls have not been reground for a considerable lengthof time since the edges of the wire are placed under greater tensilestrain before the wire is used.

My invention comprises correcting this difliculty by reducing thediameters of at least one, or several, or the majority, or all, of themajor rolls of a Fourdrinier machine beyond the normal area of drainage.Fig. 3 shows in exaggerated detail the preferred form of the invention,and Fig. 4 likewise shows in exaggerated detail a second form of theinvention. Referring to Fig.- 3 there is shown the breast roll H and,

in skeleton outline, the drain boards l3 and a table roll ll. The wireIII is indicated as extending beyond the deckle straps 28 which limitthe area of drainage. Substantially at or near the edge of the area ofdrainage the breast roll is progressively decreased in diameter towardthe end of the roll. Since the deckle straps 28 press the wire againstthe drain boards I 3 and table rolls l4 these members are preferably ofuniform diameter throughout in order to provide a level foundation forthe wire. The forming paper web 20 is shown as extending to the inneredge of the deckle straps 28. The reduction in diaineter of the roll IIis greatly exaggerated in the drawing since a reduction ofone-sixty-fourth of an inch in radius in the last several inches of theusual breast roll is usually sufflcient. The rolls i2, i1, 24, 25, 26and 21 may be similarly v treated, either alone or together with otherrolls,

but the invention is preferably applied to the breast roll or the couchroll or both of said rolls. It is therefore seen that the strains in theedge areas of the wire will be substantially the same or less than thestrains in the drainage area of thewire since, first, the rolls may beabraded and corroded to a considerable extent before their intermediatediameter become lesser than their end diameters, and secondly, the innersurface of the wire itself may be abraded and corroded to a considerableextent. As the tensioning devices take up the slack thus created in thedrainage area of the wire the sole effect will be to cause the edgeareas of the wire more closely to approach the recessed surfaces of theends of the rolls. Since the edge areas of the wire perform no usefulwork it does not matter that they may be diverted from the plane of thedrainage area of the wire, especially if the drain boards and tablerolls remain uniform throughout their lengths.

Fig. 4 discloses an extreme modification wherein the two ends of therolls are uniformly reduced in diameter beyond the drainage area. It isobvious that other modifications in contour of the reduced portions maybe provided within the purview of my invention.

It is not my intention to disclaim a similar reduction in the diametersof the ends of the table rolls ll, or areduction in the height of thebaiiie boards i3 or suction boxes l5 and i6 adjacent the edge areas ofthe wire, it being obvious that such would be within the purview of myinvention. I consider my invention to comprise lessening the totaldistance around wirecontacting elements of the machine at their endsbeyond the area of drainage in order to permit the drainage area of thewire to become worn without placing the edge areas under increasedtension.

I claim: I

In a paper making machine of the Fourdrinier type provided with theusual travelin wire, breast and couch rolls and suction devices, atleast said breast roll having a uniform diameter throughout the greaterportion of its width and having its ends decreased in diameter, saidwire being of a width equal to the overall length of the roll andgreater than the effective drainage area of said suction devices.

CASPER E. YOUNGCHILD.

